1. Field of the Invention
The present invention generally relates to an optical disc device, and more particularly, to a technology for a host to obtain in real time a current recording velocity of an optical disc device varying the recording velocity during a recording to an optical disc, chiefly a CD-R or a CD-RW.
2. Description of the Related Art
In general, optical recording media can be classified into the following three types, depending on whether or not data can be recorded thereon repeatedly: a ROM type used only for reproduction, a write-once-read-many WORM type, and a rewritable type on which data can be recorded repeatedly. The ROM-type optical recording media include a CD-ROM (Compact Disc-Read Only Memory) and a DVD-ROM (Digital Versatile Disc-Read Only Memory). The WORM-type optical recording media include a write-once CD-R (Compact Disc-Recordable) and a write-once DVD-R (Digital Versatile Disc-Recordable). The rewritable-type optical recording media, on which data can be recorded freely and repeatedly, include a CD-RW (Compact Disc-Rewritable), a DVD-RAM (Digital Versatile Disc-Random Access Memory) and a DVD-RW (Digital Versatile Disc-Rewritable).
A driver device that records information on a medium having tracks in a spiral form, represented by the above-mentioned CD-R/RW, generally adopts a Constant Linear Velocity (CLV) method. However, since a conventional device records only at a slow recording velocity, there has not been a problem that a mechanical characteristic of a medium inhibits a maximum-velocity recording. Accordingly, a recording is always performed at a velocity designated from a host, and the host can inform an operator of the designated velocity as a recording velocity. In other words, the drive device does not have to return current recording velocity information to the host during a recording.
Recently, however, a recording velocity of the above-mentioned CD-R/CD-RW drive device has rapidly been developed higher. The recording velocity is now beginning to undergo an evolution similar to an evolution of a reproducing velocity in which the reproducing velocity is increased from a limit of revolutions in a 16-fold velocity CLV reproduction to a greater degree by a PCAV (Partial Constant Angular Velocity) reproduction and a CAV (Constant Angular Velocity) reproduction, without increasing the revolutions. For example, in a recording at a 20-fold velocity at a maximum, a ZCLV (Zone Constant Linear Velocity) recording is conceivable in which data is recorded by a 16-fold velocity CLV unto a 10-minute position, and by a 20-fold velocity CLV from the 10-minute position. Also, a PCAV (Partial Constant Angular Velocity) recording is conceivable in which data is recorded by a CAV from a 16-fold velocity to a 20-fold velocity, and once the velocity reaches the 20-fold velocity, data is recorded therefrom by a 20-fold velocity CLV.
In addition, as basic recording modes for the CD-R/CD-RW, there are a disc-at-once mode and a track-at-once mode. These modes are sequential writings which do not cause an interruption of recording unless a buffer underrun occurs. Accordingly, a time required for a recording can be easily conjectured from a recording velocity and a recording capacity. A host can inform an operator of the recording velocity and the time required for the recording so that the operator can perform systematic operations. This is a feature that a storage device performing a random writing does not possess.
Besides, a motor has a limit of revolutions partly because a focus and track servo cannot be performed correctly at a high-speed revolution. This depends greatly on a formation precision of media such that the servo cannot possibly be performed correctly even at a 16-fold velocity for an inferior medium.
Whereas a high-speed recording is realized by improvements in performance of both a drive and media, a safe recording is preferable with whatever media. This highlights an importance of a technology in which a drive device perceives a limit of media so as to record data at a safe velocity, the technology being put to practical use. For example, a maximum recording velocity is restricted according as types of media; or servo status is checked before writing so as to determine a safe velocity.
As mentioned above, conventionally, a drive device records data from the start to the end at a velocity designated by a host, which did not cause a particular problem. However, now that a recording velocity is increased variably, there occurs a difference between a velocity designated by a host and a velocity at which a drive device actually records data, which makes it difficult for an operator to conjecture a time required for a recording.